The aim of this proposal is to demonstrate that the group of physicians and scientists at Children's Hospital of Philadelphia (CHOP) have the interest, infrastructure and resources to be an outstanding participant in the Biliary Atresia Neonatal Hepatitis Clinical Consortium to conduct investigations of the pathogenesis, natural history and pathophysiology of Biliary Atresia and Neonatal Hepatitis. Progress in the care of Biliary Atresia and Neonatal Hepatitis is hampered by many factors including the difficulty in recruiting adequate numbers of children with these diagnoses at a single center, diversity of conditions that are all labeled neonatal hepatitis and the absence of a national database. There are few efforts at collaboration in pediatric liver research at the national level, unlike that instituted to accelerate the pace of progress in pediatric cancer or AIDS. Success in addressing these problems through a national collaborative network will depend on the scientific leadership and operational performance of the centers involved in the Consortium. Our proposal is composed of four sections. Section I: A description of the facilities, resources and participation of the team of physicians and scientists at Children's Hospital of Philadelphia and University of Pennsylvania. Section II: A strategy and description of the development of a comprehensive database. Section III: A three-year research protocol to identify therapy to improve growth in children with Biliary Atresia. Section IV: A one-year research protocol to examine Jagged 1 as a modifier gene in children with Biliary Atresia. In summary, the CHOP team has the infrastructure, facilities, subject availability, clinical investigators and scientific investigators to be a dedicated and productive member of the Biliary Atresia Neonatal Hepatitis Clinical Consortium.